(a) Field of the Invention
The invention relates to a tone detection device and a method thereof suitable to be used in a robot, particularly to a tone detection device and a method to acquire a command in a tone.
(b) Description of the Related Art
Generally, a Goertzel filter is used to differentiate noise, mute, sound, and tone in a telecommunication system. For example, the invention disclosed in U.S. Pat. No. 6,381,330 is applied in a telecommunication system where the receiving end is via wire input and the output of the Goertzel filter is used in detection. However, in this patent, the detecting procedure is to analyze a small portion instead of analyzing a whole frame to reduce the calculation volume and then to confirm either the tone signal exists or not by determining whether the harmonic wave is generated or not. Besides, for example, the invention disclosed in U.S. Pat. No. 6,671,252 is applied in a telecommunication system where the receiving end is via wire input and the output of the Goertzel filter is used in detection. In this patent, the detecting procedure is to utilize different functions of a short frame and a long frame to increase robustness during detection. The resolution in time domain during analyzing the short frame is increased while the noise resistance during analyzing the long frame is increased. In the common telecommunication system, the transmitter and the receiver are connected via wires and signals are transmitted to the receiver though wires. If signals are wirelessly transmitted, the correctness of detecting the signals will be reduced due to the distance existed between the receiver and transmitter. Besides, specifically, as a loud-speaker utters an audio signal for being received by a microphone that is moving relative to the loud-speaker, the correctness of detecting the signals will be further reduced due to the variation of the distance between the loud-speaker and the microphone.